"Enter your name here" <ltharp at ix.netcom.com> writes:
>Re is made to the family that descendant from one of our presidents mating a
>Is there a marker on a gene (?) to indicate a black inheritance?
>Is the marker relative to the number of genereations away the original
Ummm...no. The concepts of "black" and "white" are fairly arbitrary
in a biological sense. The determination of Jefferson's descendants
was performed by comparing genes in Jefferson's accepted descendants
to those of his disputed descendants. According to the comparison,
the descendants of Jefferson's slave, who I believe was named Hemmings,
are in fact related to his descendants who bear his name.
Getting back to the original question, "blacks" are a very, very
diverse group of people (more so than those we call "white") and
using genetic means to identify them would be very difficult. In
addition, people of African decent in the US nearly all have some
European ancestors as well.
There was a great essay in a textbook entitled "Evolutionary Biology"
by Doug Futuiyama (I hope that's how his name is spelled) describing
the genetics of human populations. He makes a few specific comments
about our current ideas of "race." He mainly points out that the
trait we have adopted as definitive of someone's ancestry, which is
one's complexion, could easily be replaced with a large number of others
and would lead us to identify ourselves with completely different
groups of people.
He has a great map of the world by prevalent blood type, in which
North America and Africa are occupied by one "race," and another
stretches from Europe to China.